Filament Change -- RU-200 and RU-H2R

In order to avoid overtightening screws upon reassembly, always use the straight-handled allen head driver and not the L-shaped allen keys.

The tools used for the following operations are kept in the top large drawer of the small tool chest. The filaments are found in little styrofoam boxes in the locked cabinet above the sink.

1. Turn the X-ray off by pressing the red OFF button located on the X-ray control front panel (left side).

2. Turn the vacuum system off by pushing the red STOP button on the vacuum control front panel.

3. Wait until the Ready light is illuminated on the TMP controller (back panel) and then turn off the main power via the circuit breaker (back panel) and at the wall disconnect box.

4. Release the vacuum with the bleed valve located on the front of the tube housing using either the Rigauk made tool or a large screw driver.

5. After the vacuum has been released screw the bleed valve back into the tube housing. Do not over tighten!

6. Remove the four Phillips head screws on the front lid that covers the cathode assembly and carefully remove.

7. Loosen (but do not remove -- screw are not captive) the two Phillips head screws to the cover over the filament lead wires located below the base of the cathode. Let the cover drop down to expose the filament lead wires.

8. Unscrew the allen head screws holding the filament lead wires to the filament terminals that are protruding from the bottom of the cathode assembly. Be careful not to completely remove the screw from the filament lead wires, and keep the wires straight as they are unscrewed from the filament terminals, by pulling the filament lead wire towards you with the needle nose pliers.

9. Using lint free gloves (in the cupboard with the filaments), grasp the sides of the cathode making sure not to touch any parts in the tube housing with your bare hands. Fingerprints can adversely affect the vacuum, so use extreme care. Unscrew the two captive screws at the bottom of the cathode and remove the cathode from the tube housing. Do not completely remove the allen head screws from the cathode.

10. Place the cathode with the filament facing down on a clean working surface.

11. Remove the two large Phillips head screws on the back of the cathode and remove the back of the cathode assembly. Carefully clean the inside of the cathode with a lint free cloth and use canned air to blow any residual lint or dust off the cathode.

12. Remove the two allen head screws that secure the filament to the cathode assembly and remove the filament from the cathode. If in doubt as to which screws to remove, examine a new filament to see how it is contructed.

13. Take a new filament and place in the cathode assembly. Carefully centre the filament in the "cathode window" and re-tighten the screws holding the filament to the cathode assembly. Do not over tighten these screws or serious damage to the cathode may occur!!! Make sure that the correct filament is installed in the cathode being used (P/N 4892V1 for the 0.5mm point focus cathode).

14. Place the back on the cathode assembly and re-tighten the two Phillips head screws. Do not over tighten these screws or serious damage to the cathode may occur!!!

15. Take the cathode and insert it into its place in the tube housing and re-tighten the two allen head screws that hold the cathode into the tube housing. Do not over tighten these screws or serious damage to the cathode may occur!!!

16. Re-attach the filament lead wires to the filament protruding from the bottom of the cathode. Make sure that the wires do not touch each other or any other part in the tube housing. Use the needle nose pliers to help keep the wires straight as they are tightened.

17. Slide the filament lead wire cover over the filament lead wires (use a small screwdriver to help slide the cover up) and re-tighten the screws that hold it in place. Do not over tighten these screws!!!

18. Take the front lid (removed in step 6) and examine the O-ring for any signs of damage or lint on its surface. Clean or replace the S-110 O-ring if necessary. A thin coating of vacuum grease may be applied to the O-ring if desired, although if the O-ring is in good shape it is not necessary. Do not get the vacuum grease on any part exposed to the vacuum system, except the O-ring seat.

19. Attach the front lid to the tube housing with the four Phillips head screws. Lightly secure the screw for now.

20. Turn the main power at the disconnect box to ON and turn the main power circuit breaker to ON.

21. Turn the vacuum system on by pushing the white START switch on the vacuum controller (front panel). Quickly tighten the four Phillips head screws to the front lid in a cross bold pattern. Listen carefully to the sound of the roughing pump as the screws are tightened to make sure that the O-ring on the front lid properly seals If no noticeable sound change is heard (i.e. the roughing pump should become quieter after the screws are tightened) turn the vacuum system off and re-seat the front lid by completely removing it, checking the O-ring, and then re-attaching it to the tube housing. Again make sure that the screws are not over tightened as they are easily damaged.

22. After re-starting the vacuum system, bring up the X-rays and age the filament according to the aging schedule.

23. After aging the filament, re-align the monochromator and collimator.